The present invention relates to a direct current backup power device of an electrical data processing system comprising at least one computer supplied with very low voltage. It also relates to an installation comprising such a device.
More precisely, it applies to a data processing system whose direct current power supply is intended to be connected to an alternating current supply system by means of an AC/DC converter of alternating current into very low voltage direct current.
“Very low voltage” is understood to mean a voltage generally qualified as “safety voltage” which enables an operator to handle any electrical component safely under this voltage. Such a voltage is furthermore generally adapted to the electronic components of a data processing system. Several domains are defined legally in France and in Europe (TBT, TBTS, TBTP, TBTF) but all place very low voltages under the threshold of 120 V direct current and under the threshold of 50 V alternating current.
The voltage of an alternating current distributed by an electrical power distribution system is generally in the order of 220/230 V, which therefore a priori represents a danger for an operator. However, it is generally considered that a voltage of 50 V or less does not represent a danger when handled. So, in telecommunication applications, the transmission data processing systems are generally subject to a voltage of about 48 V. In the field of aeronautics, the on-board components are generally subject to a direct voltage of about 24 V. Lastly, a data processing system of the computer type is generally subject to a direct voltage of about 12 V.
A data processing system is for example a set of computer servers interconnected in a local network thus forming a high performance computer generally qualified as a HPC (High Performance Computing) computer. In this case, as in other sensitive applications (computer server, fixed or portable microcomputer, telecommunication radio-frequency station, etc.), it is important that the operation of the electrical system is not disturbed by micro-cuts of the alternating current supply system. Indeed, such micro-cuts, even when they only last for a few hundred milliseconds or so, can bring about calculation errors, data losses or highly penalizing malfunctions of the HPC computer.
However, such micro-cuts are fairly frequent as the controller of the alternating current supply system can occasionally need to shed the load of parts of the system. They generally have a duration equivalent to a few periods of the alternating current: for an alternating current of 50 Hertz, a micro-cut of ten to twelve periods thus lasts between 200 and 250 milliseconds. Furthermore, the restarting of the AC/DC converter following a micro-cut can also take 100 to 200 milliseconds, which gives a micro-cut, viewed from the electrical system, that can last up to 450 milliseconds.
Installations comprising an electrical system for data processing, of the system micro-cut sensitive type, generally provide an uninterruptible power supply device which makes it possible to provide a stable power supply without micro-cuts, whatever happens on the alternating current supply system. This uninterruptible power supply is generally directly connected to the supply system and therefore comprises a rectifier for alternating current conversion into direct current. Furthermore, it is fitted with an energy storage device, such as a storage battery or a set of super-capacitors, and with an uninterruptible power supply to convert the direct current generated by the energy storage device into an alternating current. Inserted between the alternating current supply system and the AC/DC converter of the installation, it therefore substitutes for the supply system to provide electrical energy to the electrical system during micro-cuts. Such an uninterruptible power supply device is for example described in Sukumara et al's article called “Fuel cell based uninterrupted power sources”, published in 1997 International Conference on Power Electronics and Drive Systems Proceedings, vol. 2, pages 728-733, 26-29 May 1997.
As disclosed in the European patent application published under the EP 1 639 684 number, the energy storage device can be composed of super-capacitors arranged in series for a greater rapidity in charging electrical energy. This charging is ensured by a charger supplied either with direct current, when the power supply is independent of the supply system, or when the alternating current of the supply system has been beforehand converted into direct current, or with alternating current, in which case the charger must comprise its own AC/DC converter.
More precisely, in the European patent application published under the EP 1 661 226 number, a super-capacitor-based storage module charger is described. This charger is supplied with an energy source such as a fuel cell, a battery, or another energy source, which can in particular be a source of alternating current combined with an AC/DC converter.
In all the cases, an uninterruptible power supply device such as the aforementioned ones has a certain bulkiness. Furthermore, if a strong current must be provided in a discharging situation, it is sometimes necessary to make provision for the arrangement of several of these uninterruptible power supply devices in parallel.
It may therefore be desirable to provide a direct current backup power supply device that can overcome at least one part of the aforementioned problems and constraints.